1. Field of the Invention
In one aspect this invention relates to the axial alignment of mechanical parts. In yet a further aspect, this invention relates to an improved means for aligning pulleys to prevent destruction of drive belts.
2. Prior Art
Belt drives connecting pulleys are a common means to transfer power from a prime mover to one or more devices. The common V-belt used in land vehicles is the best known example of this type of drive. The V-belts are used to drive a number of components including: alternators, power steering pumps, and power brakes. When a belt breaks or moves off one of the pulleys, a system failure occurs creating an inconvenience at best and an unsafe situation at worst.
It is common to align pulleys by placing a steel rule or other straight edge in the grooves of the pulleys and attempting to align the straight edge by eye. This system provides a minimally acceptable system for standard V-belt drives with small power requirements, where a failure has minimal consequences, and the belts are relatively narrow; however in high load applications or where failure can be catastrophic, misalignment is a greater problem.
In the combat vehicle systems used by military forces, the vehicle prime mover uses a poly-V- belt to power a 24 volt alternator which in turn powers the electrical system that operates all the vehicle systems. Failure of the belt drive will result in a failure of the majority of the vehicle systems. Thus a belt failure will effectively disable the vehicle exposing the crew to the dangers inherent in combat situations. To properly transfer the amount of power required by combat vehicle systems a wide polyvee type belt is generally used. Belts of this description are wide relative to the normal drive belts and require wider pulleys. Such pulleys are more difficult to align and any misalignment will cause the belt to jump off the pulleys.
In wide belt systems when the pulleys are not properly aligned so the axis of rotation of one pulley is the same as the rotational axis of the other pulley with respect to all three degrees of freedom, x, y and z, the belt will tend to "walk" off one of the pulleys disabling the system.
The problem becomes more pronounced the greater the power and the speed. In combat vehicles the alignment must often be made under field conditions where sophisticated equipment is not available and the pulleys must still be accurately aligned. Prior to the present device, pulleys were frequently misaligned using the straight edge method described above when vehicles were repaired under field conditions. Consequently belt failures where the belt came off the pulleys disabling the vehicle were common. There was a need for an alignment device which was strong, light weight, and which could align the pulleys to an accuracy of about 0.2 degrees.